ES2617621T3 - 3-ketocoumarins for LED curing - Google Patents

Abstract

A process for curing light-curing compositions, a process comprising: I) preparing a light-curing composition comprising: a) from 50 to 99.9% by weight of at least one ethylenically unsaturated compound; b) 0.1 to 35% by weight of at least one 3-ketocoumarin of formula I: ** Formula ** in which: R1 is a substituted or unsubstituted C2-C12 alkyl group; Cou is a coumarin group of the formula: ** Formula ** in which: R2, R3, R4 and R5 are, independently of each other, hydrogen; or -S-R7, where R7 is hydrogen, C1-C12 alkyl, C3-C12 alkenyl, substituted or unsubstituted phenyl, aryl or heteroaryl, C5-C6 cycloalkyl, C1-C12 alkyl which is substituted with SH, -N (C1 alkyl -C6) 2, piperidino, morpholino, piperazino, -OH, -O (C1-C12 alkyl), -COOH; or C1-C12 alkoxy; R6 is hydrogen, a hydroxyl group, an alkyl group having 1 to 4 carbon atoms; or Cou is a substituted or unsubstituted naphtho-coumarin group of the formula: ** Formula ** with the proviso that at least one of R2, R3, R4 and R5 is different from H and that, when Cou is (a) and at least one of R2, R3, R4 and R5 is C1-C12 alkoxy or when Cou is (b), (c) or (d), R1 is a substituted or unsubstituted C1-C12 alkyl group; ** Formula ** II) photopolymerize the photopolymerizable composition thus obtained with an LED light source that emits at wavelengths between 365 nm and 420 nm.

Description

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3-ketocoumarins for LED curing Technical field

The present invention relates to 3-ketocoumarins that can be used as photoinitiators in the LED curing and a method of curing compositions comprising said 3-ketocoumarins.

Prior art

Photopolymerizable systems contain photoinitiators that have a functional group in the molecule that, by exposure to light radiation of the appropriate wavelength, generate radicals capable of initiating polymerization.

Among the light radiation sources used in this field, light emitting diodes (LEDs), a semiconductor light source, have undergone significant development in recent years due to the advantages of low temperature operation and useful life. extremely long compared to conventional medium pressure mercury arc curing lamps. LED lamps are advantageous because of the inherently small size of LED units, their longer life, their robustness and their ability to be easily designed, for example by forming commercial printing systems.

When LED lamps are used to cure inks and coatings, it is necessary to use selected photoinitiator systems that are tuned to the wavelength of this light source. Although mercury arc lamps typically have a polychrome emission spectrum, emitting light in all regions of the UV-visible spectrum of 200 to 450 nm, LED lamps usually have a single emission band in the 365-420 nm range. .

Thus, photoinitiators are required, which absorb in the region between 365 nm and 420 nm, to make full use of the recent development of LEDs of increasing power. In addition, since a high concentration of photoactive substance is usually required for LED applications, photoinitiators should have high compatibility with the photopolymerizable system. Thioxanthones, such as isopropyl thioxanthone (ITX) and its derivatives, and acylphosphine oxides are photoinitiators commonly used in this field.

Unfortunately, thioxanthone derivatives commonly used as photoinitiators and as sensitizers are likely to turn yellow when exposed, thereby forming degradation products with limited stability. Consequently, the original yellowing may change unpredictably when stored. Especially in image formation, for example, in inkjet printing, this unstable yellowing behavior makes it very difficult to control the tone of the image in the final image.

Acylphosphine oxide initiators, on the other hand, result in degradation products of volatile aldehyde type media that produce a background odor in cured coatings or in the printed image, which is also not acceptable. In addition, the use of large amounts of acylphosphine oxide initiators creates several health and safety problems.

Alpha-diketones, such as camphorquinone and its derivatives and 1-phenyl propandione, are examples of different photoinitiators that have been used in combination with LED light sources, particularly for dental applications, but, unfortunately, their activity is very low, in particular in a pigmented system.

Therefore, there is a growing demand for the development of different photoinitiators, which absorb in the region between 365 nm and 420 nm, that have a predictable yellowing behavior, good photochemical reactivity, no odor degradation product and no health inconvenience or safety. Coumarin derivatives have long been proposed as photoinitiators and, in particular, as sensitizers that operate at wavelengths of up to about 550 nm, but always using broad-spectrum actinic lamps.

GB 1,578,662 discloses a composition comprising a radiation-sensitive unsaturated material or a photopolymerizable azide material, which contains, as sensitizer, a substituted 3- coumarin compound, which can also be a 3-ketocoumarin. US 4,278,751 discloses a photopolymerizable composition containing at least one polymerizable compound containing ethylenic unsaturations, a photopolymerization activator (photoinitiator) and a substituted amine ketocoumarin sensitizer. Light sources that can be used include broad-spectrum, filtered or unfiltered light sources, including xenon or carbon arcs and narrow-spectrum sources, such as mercury lamps.

US 4,289,844 discloses a photopolymerizable composition containing at least one polymerizable compound having a polymerizable compound containing an ethylenic unsaturation, a photopolymerization activator (photoinitiator) and a sensitizer, selected from 3-ketocoumarins containing a

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Ci-C12 alkyl or alkenyl group or a carbocyclic group or a heterocyclic group having 5-20 carbon atoms and heteroatoms. In this patent a medium pressure mercury lamp is used as a light source.

EP 2 388 146 discloses a printing process comprising a first step of printing an ink composition comprising a coumarin, a photopolymerization initiator, an ethylenically unsaturated compound and a dye in a material to be printed, and an ultraviolet irradiation curing stage having a maximum wavelength between 375 and 395 nm by means of a light emitting diode to cure the printed ink composition.

WO 2008/040650 discloses a photocurable composition comprising (a) at least one ethylenically unsaturated photopolymerizable compound, which is a polyester acrylate, (b) at least one photoinitiator of the phenylglyoxylate type, and (c) at least one dye, which is a non-white dye absorbing UV light and visible short.

The inventors found with surprise that specific derivatives of aromatic 3-ketocoumarins have a high curing rate when exposed to a LED light source with a wavelength between 365 and 420 nm compared to photoinitiators of the state of the art and with others 3-ketocoumarins. They do not exhibit the unwanted yellowing behavior and at the same time maintain superior compatibility with light-curing systems.

Therefore, the object of the present invention are specific aromatic derivatives of 3-ketocoumarin and a method of curing photopolymerizable compositions, including these aromatic derivatives as photoinitiators and as sensitizers. It has been found that such photopolymerizable compositions are suitable for inclusion in ink or coating compositions that are curable upon exposure to radiation from an LED light source.

In this text, "sensitizer" means a compound that, by an energy transfer process, activates the photoinitiator at a wavelength in which the photoinitiator by itself will not be reactive.

Description of the invention

An object of the present invention is a process for curing light-curing compositions, a process comprising:

I) prepare a photopolymerizable composition comprising:

a) 50 to 99.9% by weight, preferably 70 to 98.9% by weight, of at least one ethylenically unsaturated compound;

b) 0.1 to 35% by weight, preferably 0.1 to 20% by weight, and more preferably 0.2 to 15% by weight, of at least one 3-ketocoumarin of formula I:

image 1

in which:

R1 is a substituted or unsubstituted C2-C12 alkyl group; Cou is a coumarin group of formula:

image2

in which:

R2, R3, R4 and R5 are, independently of each other, hydrogen; or -S-R7, where R7 is hydrogen, C1-C12 alkyl, C3-C12 alkenyl, substituted or unsubstituted phenyl, aryl or heteroaryl, C5-C6 cycloalkyl, C1-C12 alkyl which is substituted with SH, -N (C1 alkyl -C6) 2, piperidino, morpholino, piperazino, -OH, -O (C1-C12 alkyl), -COOH; or C1-C12 alkoxy; and at least one of R2, R3, R4 and R5 is different from H;

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R6 is hydrogen, a hydroxyl group, an alkyl group having 1 to 4 carbon atoms; or Cou is a substituted or unsubstituted naphtho-coumarin group of formula:

image3

with the proviso that at least one of R2, R3, R4 and R5 is different from H and that, when Cou is (a) and at least one of R2, R3, R4 and R5 is C1-C12 alkoxy or when Cou is (b), (c) or (d), R1 is a substituted or unsubstituted C1-C12 alkyl group;

II) photopolymerize the photopolymerizable composition thus obtained with an LED light source that emits at wavelengths between 365 nm and 420 nm.

A further object of the present invention are 3-ketocoumarins of formula I:

image4

in which:

R1 is a substituted or unsubstituted C2-C12 alkyl group;

Cou is a coumarin group of formula:

image5

wherein at least one of R2 R3, R4 and R5 is an alkoxy group having 1 to 6 carbon atoms and R6 is hydrogen, a hydroxyl group or an alkyl group having 1 to 4 carbon atoms;

or Cou is a substituted or unsubstituted naphthocoumarin of formula:

image6

They are another object of the present invention 3-ketocoumarins of formula I:

image7

in which:

R1 is hydrogen or a substituted or unsubstituted C1-C12 alkyl group; 5 Cou is a coumarin group of formula:

image8

wherein at least one of R2, R3, R4 and R5 is -S-R7, where R7 is hydrogen, C1-C12 alkyl, C3-C12 alkenyl, phenyl, aryl or substituted or unsubstituted heteroaryl, C5- cycloalkyl C6, C1-C12 alkyl which is substituted with SH, - N (C1-C6 alkyl) 2, piperidino, morpholino, piperazino, -OH, -O (C1-C12 alkyl), -COOH, and R6 is hydrogen, a group hydroxyl or an alkyl group having 1 to 4 carbon atoms.

10 Detailed description of the invention

In the present text, the terms "alkyl" or "alkyl group" mean, when something different is not indicated, a linear or branched alkyl chain containing 1 to 12 carbon atoms and includes all possible variants for each number of atoms. carbon in the alkyl group; that is, for three carbon atoms: n-propyl and isopropyl; for four carbon atoms: n-butyl, isobutyl and tert-butyl; for five carbon atoms: n-pentyl, 1,1-dimethyl-propyl, 2,2-dimethylpropyl and 2-methyl-butyl.

The terms "cycloalkyl" or "cycloalkyl group" mean, when not indicated otherwise, an aliphatic ring containing from 4 to 12 carbon atoms that can be, for example, cyclopentyl, cyclohexyl, cyclooctyl, cyclododecyl.

The terms "aryl" or "aryl group" mean, for example, a substituted or unsubstituted phenyl group, a substituted or unsubstituted naphthyl group, an anthracenyl group, an indenyl group, a fluorenyl group and others.

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The terms "heteroaryl" or "heteroaryl group" mean, for example, furan, thiophene, pyrrole, oxazole, isooxazole, thiazole, isothiazole, imidazole, pyrazole, pyran, pyridine, pyrrolidine, piperidine, indole, quinoline, isoquinoline, xanthene, carbazole , acridine, indelina, julolidine and others.

"Alkenyl" or "alkenyl group" means an unsaturated group containing from 3 to 12 carbon atoms that can be, for example, allyl, metalyl or undecenyl.

The term "substituted" means that a group carries a substituent which may be a halogen atom, an alkyl, cycloalkyl, alkoxy, alkylamino, dialkylamino, alkylthio or arylthio group, heterocyclic groups, more specifically, methyl, ethyl, isopropyl, tert-butyl , phenyl, trifluoromethyl, cyano, acetyl, ethoxycarbonyl, carboxy, carboxylate, amino, methylamino, dimethylamino, ethylamino, diethylamino, isopropylamino, diisopropylamino, cyclohexylamino, dicyclohexylamino, acetylamino, piperidino, pyrrolidyloxy, methoxy, pexy , phenoxy, hydroxy, acetoxy, - PO3H, methylthio, ethylthio, i-propylthio, n-propylthio, phenylthio, mercapto, acetylthio, thiocyan, methylsulfinyl, methylsulfonyl, dimethylsulphonyl, sulfonate groups, fluorine atom, chlorine atom, bromine atom , iodine atom, trimethylsilyl, triethylsilyl, trimethylstannyl, furyl, thienyl, pyridyl, piperidino, morpholino, pyrrolidyl, etc. groups.

Among the substituents mentioned in the preceding paragraph, electron donor groups are preferably contained, such as alkoxy groups, for example methoxy, ethoxy, isopropoxy, tert-butoxy or phenoxy groups; methyl, ethyl, isopropyl, hydroxy, acetoxy, benzoyloxy, or a thioalkyl group groups, such as methylthio, ethylthio, n-propylthio, i-propylthio, butylthio, pentylthio, or an arylthio group, such as phenylthio.

Ri in formula I is preferably a substituted or unsubstituted C2-C12 alkyl group, more preferably a C2-C6 alkyl group having 2 to 6 carbon atoms.

For the realization of the present invention 3-ketocoumarins of formula I are preferred, in which Cou is a coumarin group of formula (a) in which at least one of R2 R3, R4 and R5 is a C1-C6 alkoxy group, in particular a C1-C3 alkoxy group, or is -S-R7, where R7 is an alkyl group having 1 to 6, in particular 1 to 3, carbon atoms.

Preferably, R6 is hydrogen.

In another preferred embodiment of the present invention, Cou is an unsubstituted naphtho-coumarin group of formula (b), (c) or (d).

In another preferred embodiment, in the 3-ketocoumarin of formula I, Cou is a coumarin group of formula (a) in which R6 is hydrogen, at least two of R2 R3, R4 and R5 are a C1-C6 and R1 alkoxy group it is a substituted or unsubstituted C1-C12 alkyl group.

The compounds represented by formula I can be prepared according to conventional procedures known to the person skilled in the art. For example, they can be synthesized by means of a Knoevenagel condensation of 2-hydroxy-1-arylaldehyde (-aryl ketone) with the corresponding alkyl benzoylacetate, as follows:

image9

The light-curing compositions of the invention can also conveniently include a co-blender, which is a molecule that acts as a hydrogen donor that increases the rate of polymerization. Co-initiators are known in the art and are usually alcohols, thiols, amines or ethers that have an available hydrogen, linked to a carbon adjacent to the heteroatom. Such coinitiators are generally present in an amount between 0.2 and 15% by weight, preferably 0.2 to 8% by weight. Suitable co-initiators include, without limitation, aliphatic, cycloaliphatic, aromatic, arylaliphatic, heterocyclic, oligomeric or polymeric amines. They can be primary, secondary or tertiary amines, for example butyl amine, dibutyl amine, tributyl amine, cyclohexyl amine, benzyl dimethyl amine, di-cyclohexyl amine, N-phenyl glycine, triethyl amine, phenyl-dietanol amine, triethanolamine, piperidine, piperazine, morpholine, pyridine, quinoline, esters of benzoic dimethylamino acid, Michler's ketone (4,4'-bis-dimethyl aminobenzophenone) and the corresponding derivatives.

As an amphnic coinitiator, an amine modified acrylate compound can be used, including examples of such amine modified acrylate modified by reacting with a primary or secondary amine described in US 3,844,916, EP 280222, US 5,482,649 or US 5,734,002. Preferred co-initiators are Esacure A198 (bis-N, N- [4-dimethylaminobenzoyl) oxyethylene-1-yl] -methylamine) and Esacure EDB (ethyl-4-dimethylamino benzoate), both marketed by Lamberti SpA, IT, 2-ethylhexyl- 4-dimethylaminobenzoate and N-phenyl glycine. The

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Light-curing compositions of the invention may also conveniently include other photoinitiators commonly used in the field. Examples of photoinitiators that can be used in combination with the 3- ketocoumarins of formula I include acylphosphine oxides, both mono-acylphosphine oxides and bisacylphosphine oxides, coumarins or other ketocoumarins, aromatic compounds of onium salts, organic peroxides, thioxanthones, hexaaryl bisimidazoles , ketoxime esters, borate compounds, acinium compounds, metallocene compounds, benzophenones, a-diketones, ketosulfones, a-amino ketones, benzofna and ethers of benzofna, benzyl ketals, a-hydroxyketones and mixtures thereof. Examples of thioxanthone derivatives are thioxanthone, diethylthioxanthone, 2-isopropylthioxanthone, 2-chlorothioxanthone, 2,4-diethylthioxanthone or those described in PCT / EP2011 / 069514, such as n-dodecyl-7-methyl-thioxanthone-3 -carboxylate and N, N-diisobutyl-7-methyl-thioxanthone-3- carbamide. Examples of a-hydroxyketones and a-amino ketones are 1-hydroxy cyclohexylphenyl ketone, 2-hydroxy-2-methyl-1- phenyl-propan-1-one, 1- [4- (2-hydroxyethoxy) phenyl] -2-hydroxy -2-methyl-1-propan-1-one, 2-hydroxy-1- {4- [4- (2-hydroxy-2-methyl-propionyl) -benzyl] phenyl} -2-methyl-propan-1- one), 2-methyl-1- (4-methylthiophenyl) -2-morpholinopropan-1-one), 2-benzyl-2- dimethylamino-1- (4-morpholinophenyl) -butanone-1, and (2- (dimethylamino) ) -2 - [(4-methylphenyl) methyl] -1- [4- (4-morpholinyl) phenyl] -1-butanone). Examples of oxime-based photoinitiators are 1,2-octanedione, 1- [4- (phenylthio) phenyl] -, 2- (O-benzoyloxime) and ethanone, 1- [9-ethyl-6- (2-methylbenzoyl) -9H-carbazol-3-yl], 1- (O-acetyloxime).

Examples of acylphosphine-based photoinitiators include, without limitation, bis (2,4,6-trimethylbenzoyl) phenylphosphine oxide, 2,4,6-trimethylbenzoyl diphenyl phosphine oxide and bis (2,6-dimethoxybenzoyl) oxide -2,4,4-trimethylpentyl phosphine.

Examples of coumarin derivatives may include 4-methyl-7-dimethylamino coumarin, 4-methyl-7-ethylamino coumarin, 4- methylpiperidino [3,2-g] coumarin, 4-methyl-7-cyclohexyl amino coumarin, 4-trifluoromethyl -7-diethylamino coumarin, 3-phenyl-4- methyl-7-diethylamino coumarin, 3- (2'-N-methyl benzimidazoyl) -7-diethylamino coumarin, 4-trifluoromethyl-6-methyl-7-ethylamino coumarin and 3 -phenyl-7-amino coumarin.

Other specific examples of photoinitiators include acetophenone, acetylphenone benzyl ketal, 2,2-dimethoxy-2- phenylacetophenone, xanthone, fluorenone, anthraquinone, 3-methylacetophenone, 4-chlorobenzophenone, 4,4'-dimethoxybenzophenone, 4,4'-diaminobenzene Phenone, Michler's ketone, benzofna propyl ether, benzofna ethyl ether and dimethyl benzyl ketal.

Additional preferred photoinitiators are acylphosphine oxides, a-hydroxyketones, a-amino ketones, ketosulfones, alpha-diketones and bifunctional photoinitiators, for example Esacure 1001 and Esacure ONE (both marketed by Lamberti S.p.A., IT).

The additional photoinitiators or a mixture of different photoinitiators can be added to the light-curing compositions of the invention in an amount between 0.5 and 15% by weight, preferably between 1 and 8% by weight.

In a particularly preferred embodiment of the invention, the 3-ketocoumarins of formula I are used as sensitizers of sensitizable photoinitiators in photopolymerizable compositions.

In this case, the photopolymerizable composition comprises from 70 to 98.9% by weight of at least one photopolymerizable compound, from 0.1 to 10% by weight of at least one 3-ketocoumarin of formula I, as sensitizer and 1 at 15% by weight of at least one sensitizable photoinitiator, for example a ketosulfone or an a-amino ketone and, optionally, 0.2 to 8% by weight of a coinitiator.

Preferred sensitizable photoinitiators are 1- [4 - [(4-benzoyl-phenyl) -thio] -phenyl] -2-methyl-2 - [(4-methyl-phenyl) -sulfonyl] -propan-1-one (Esacure 1001, from Lamberti SpA), 2-methyl-1- (4-methylthiophenyl) -2-morpholinopropan-1-one), 2-benzyl-2- dimethylamino-1- (4-morpholinophenyl) -butanone-1 and (2 - (dimethylamino) -2 - [(4-methylphenyl) methyl] -1- [4- (4-morpholinyl) phenyl] -1-butanone).

With ethylenically unsaturated compound is meant a monomer, an oligomer, a prepolymer having at least one unsaturated double bond, or a mixture thereof, capable of undergoing radical polymerization. Combinations of monomers, oligomers and prepolymers with different degrees of unsaturation can also be used.

Suitable monomers for the implementation of the present invention are those commonly used in the specialty and can be chosen, for example, from vinyl ethers, N-vinyl pyrrolidone, N-vinyl caprolactam, mono and polyfunctional aliphatic ethers, such as diallylic ether of Trimethylol propane, styrenes and alpha-methyl styrenes, esters of (meth) acrylic acid with aliphatic alcohol, glycols, polyhydroxy compounds such as pentaerythritol or trimethylol, propane, esters of vinyl alcohol with acrylic or aliphatic acid, derivatives of smoking and maleic acids.

Oligomers or prepolymers suitable for the present invention comprise, for example, polyesters, polyacrylates, polyurethanes, epoxy resins, polyethers with acrylic, maleic or smoking functionalities.

Monomers, oligomers and prepolymers that are commonly used in light-curing ink are preferred. These compounds are well known to those skilled in the art and are described, for example, in EP 1911814, US 2012/029108, US 2011/0074897, WO 2006/102524 and EP 2388146. Specific examples include

monofunctional, difunctional and polyfunctional monomers such as the compounds represented by the formulas documented below:

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In addition to the aforementioned compounds, other components normally used in the art and known to those skilled in the art can be added to the photopolymerizable compositions of the invention. For example, thermal stabilizers, photooxidation stabilizers, antioxidants, fillers, dispersants, coloring and / or opacifying substances and other general purpose additives. Other components of the photopolymerizable compositions of the invention may be non-photopolymerizable polymers present as chemically inert substances, for example nitrocellulose, polyacrylic esters and polyolefins.

The process claimed in the present invention is useful in coating metal, wood, paper and plastic surfaces.

The 3-ketocoumarins of formula I work both in transparent photopolymerizable compositions and in non-transparent or colored compositions and, in particular, are useful for the preparation of photopolymerizable inks with an LED light source. These photoinitiators are particularly suitable for the preparation of photopolymerizable inks for inkjet printing.

For this reason, the photopolymerizable composition of the invention may also comprise 0.01 to 30% by weight of dyes.

The dyes that can be used in the inks of the invention photopolymerizable by LED are stains, pigments or a combination thereof. organic and / or inorganic pigments can be used. The dyes are preferably pigments or polymeric dyes, most preferably pigments. The pigments can be black, white, turquoise, magenta, yellow, red, orange, violet, blue, green, brown and mixtures thereof.

Exemplary organic pigments include insoluble azo pigments, condensed azo pigments, azo lacquer and chelate azo pigments; polycyclic pigments, such as phthalocyanine pigments, perylene and perinone pigments, anthraquinone pigments, quinacridone pigments, dioxane pigments, thiondigo pigments, isoindolinone pigments and quinoftalone pigments; staining chelates, such as basic staining chelates and acid staining chelates; staining lacquers, such as basic staining lacquers and acid staining lacquers; and nitropigments, nitrous pigments, aniline black and fluorescent pigments.

For white LED photopolymerizable inks, white dyes are preferably present in an amount of 3% to 30% by weight of the ink composition, and more preferably 5% to 25%. Usually, the other dyes are present in the inks of the invention photopolymerizable by LED in the range of 0.01 to 10% by weight, preferably in the range of 0.1 to 5% by weight. Dyes are particularly preferred for inkjet printing.

In addition to the main components, LED photopolymerizable inks may also contain other specific ingredients such as co-initiators and other photoinitiators, such as those described in the preceding paragraphs and, in the same amount, dispersants, surfactants and other additives that are well known for The expert in the art. The choice of these components is not limited in particular.

Dispersants are added to the inks to improve pigment dispersibility. For the implementation of the present invention, a dispersant may be used that is generally used to prepare a liquid dispersed in pigment, such as a polymeric dispersant. Examples of such polymeric dispersants include polyoxyalkylene, polyalkylene polyamines, vinyl polymers and copolymers, acrylic polymers and copolymers, polyester, polyamides, polyimides, polyurethanes, amino polymers, silicon-containing polymers, sulfur-containing polymers, polymers fluorine and epoxy resins.

Examples of preparation of 3-ketocoumarins of formula I and photopolymerizable compositions according to the invention are documented in the following paragraphs, for illustrative and non-limiting purposes only.

Examples

Example 1 (comparative)

Preparation of 3-benzoyl-7- (N, N-diethylamino) coumarin

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0.49 g (2.58 mmol) of ethyl benzoylacetate and 0.3 g (3.52 mmol) of piperidine were added with stirring to a solution of 0.5 g (2.58 mmol) of 4- (N, N-diethylamino) -2-hydroxy-benzaldehyde in 10 ml of ethanol. After 2 hours at reflux, the reaction mass was cooled.

After crystallization at room temperature, the reaction product was filtered and dried, obtaining 0.6 g (1.86 mmol, 72% yield) of yellow crystals.

m.p. 147-150 ° C

1 H-NMR (CDCl 3, 5 ppm): 1.24 (t, 6H), 3.45 (q, 4H), 6.50 (d, 1H), 6.62 (dd, 1H).

7.55 (m, 1H), 7.81 (d, 2H), 8.09 (s, 1H).

Example 2 (comparative)

Preparation of 2,3,5,6-1H, 4H-tetrahydroquinolizino [9,9a, 1-gh] coumarin, 9-benzoyl

image14

7.35 (d, 1H), 7.45 (m, 2H),

0.21 g (1.10 mmol) of ethyl benzoylacetate and 0.21 g (1.10 mmol) of piperidine were added with stirring to a solution of 0.3 g (1.10 mmol) of 2.3.6 , 7-tetrahydro-8-hydroxy-1H, 5H-benzo [ij] quinolizine-9-carboxaldehyde in 10 ml of ethanol. After two hours at reflux, the reaction mass was cooled to room temperature and the solvent was removed by vacuum distillation. The reaction product was purified by flash column chromatography on silica gel (methylene chloride), obtaining 0.3 g (0.68 mmol, yield 78%) of orange-red crystals.

m.p. 194-196 ° C

1 H-NMR (CDCla, 5 ppm): 2.00 (m, 4H), 2.28 (t, 2H), 2.94 (t, 2H), 3.35 (m, 4H), 6.95 ( s, 1H), 7.45 (t, 2H),

7.55 (m, 1H), 7.81 (d, 2H), 8.03 (s, 1H).

Example 3 (comparative)

Preparation of 3-benzoyl-7-methoxycoumarin

image15

0.37 g (1.90 mmol) of ethyl benzoylacetate and 0.16 g (1.90 mmol) of piperidine were added with stirring to a solution of 0.3 g (1.90 mmol) of 4-methoxy-2 -hydroxy-benzaldehyde in 7 ml of ethanol. After two hours at reflux the reaction mass was cooled to room temperature and the solvent was removed by vacuum distillation. The reaction product was purified by flash column chromatography on silica gel (methylene chloride: ethyl acetate 95: 5), obtaining 0.42 g (1.49 mmol, yield 78%) of clear yellow crystals.

m.p. 150-153 ° C; 1H-NMR (CDCla, 5 ppm): 3.91 (s, 3H), 6.90 (m, 2H), 7.42-7.51 (m, 3H), 7.60 (m, 1H), 7.86 (d, 2H), 8.10 (s, 1H).

Example 4

Preparation of 7-methoxy-3- (4-tert-butyl-benzoyl) coumarin

image16

Preparation of methyl 3- (4-t-butylphenyl) -3-oxo-propanoate

15.6 g (0.129 mmol) of 33% NaOH was added dropwise to a solution of 15 g (0.129 mmol) of methyl acetoacetate in a 50% THF / water solution at 0 ° C with stirring.

5 After 90 min, 25.5 g (0.135 mmol) of 4-t-butyl benzoyl chloride were added and the mixture was heated to 60 ° C with stirring for 60 min. After cooling to room temperature, the reaction mass was diluted with 200 ml of water and 200 ml of methylene chloride. The organic phase was separated and anhydrated with sodium sulfate. The solvent was removed by vacuum distillation, obtaining crude methyl 3- (4-t-butylphenyl) -3-oxo-propanoate as a yellow oil.

10 Preparation of 7-methoxy-3- (4-tert-butylbenzoyl) coumarin

0.76 g (3.28 mmol) of methyl 3- (4-t-butylphenyl) -3-oxo-propanoate were added to a solution of 0.5 g (3.28 mmol) of 4-methoxy-2- hydroxybenzaldehyde and 0.28 g (3.28 mmol) of piperidine in 10 ml of ethanol. The solution was stirred at reflux for 2 hours. After cooling to room temperature, the solvent was removed by vacuum distillation. The reaction product was purified by flash column chromatography on silica gel (methylene chloride: ethyl acetate 95: 5), obtaining 0.50 g (1.48 mmol, 50% yield) of clear yellow crystals.

m.p. 123-127 ° C

1 H-NMR (CDCl 3.6 ppm): 1.30 (s, 9H), 3.86 (s, 3H), 6.75-6.90 (m, 2H), 7.40-7.50 ( m, 3H), 7.76 (d, 2H), 8.00 (s, 1H).

Example 5

Preparation of 3- (4-tert-butylbenzoyl) benzo [f] coumarin

image17

Preparation of 2-hydroxy-naphthalene 1-carbaldehfdo

66 g of a 33% aqueous NaOH solution (520 mmol) were added to a solution of 15 g (104 mmol) of 25 2-hydroxynaphthalene in 200 ml of methanol. After 30 min with stirring, 20 g (165 mmol) of trichloromethane were added slowly maintaining the temperature at 60 ° C. After 2 hours, the reaction mixture was cooled to room temperature and the solvent was removed by vacuum distillation. The reaction product was dissolved in 200 ml of methylene chloride and washed with 100 ml of 5% hydrochloric acid. The organic phase was separated and, after evaporation of the solvent in vacuo, the 2-hydroxy-naphthalene 1-carbaldehyde was purified by flash column chromatography on silica gel (toluene), obtaining 8.7 g (yield 48%) of white crystals.

1 H-NMR (CDCla, 6 ppm): 7.25 (d, 1 H), 7.45 (t, 1 H), 7.63 (t, 1 H), 7.80 (d, 1 H), 8.00 ( d, 1H), 8.38 (d, 1H), 10.84 (s, 1H). Preparation of 3- (4-tert-butylbenzoyl) benzo [f] coumarin

1.6 g (6.83 mmol) of crude methyl 3- (4-t-butylphenyl) -3-oxo-propanoate, prepared as documented in Example 4, and 0.4 g (4) were added , 64 mmol) of piperidine with stirring to a solution of 0.8 g (4.64 mmol) of 2-hydroxynaphthalene 1-carbaldehyde in 10 ml of ethanol. After two hours at reflux, the reaction mixture was cooled. The reaction product, crystallized at room temperature, was recovered by filtration. 0.76 g (47% yield) of product were obtained.

m.p. 161-163 ° C

1 H-NMR (CDCI3, 8 ppm): 1.35 (s, 9H), 7.48-7.56 (m, 3H), 7.58-7.65 (t, 1H), 7.68-7 , 75 (t, 1H), 7.85-7.90 (m, 2H), 7.92-7.70 (d, 1H), 8.08-8.12 (d, 1H), 8.23 -8.28 (d, 1 H), 8.87 (s, 1 H).

Example 6

5 Preparation of 7-etiIthio-3-benzoiIcumarin

image18

Preparation of 4-etiIthio-2-hydroxy-benzaIdehfdo

3 g (19 mmoIes) of 3-etiIthio-phenoI were added with stirring in a nitrogen atmosphere at a solution of 1.76 g (58.2 mmoi) of anhydrous paraformaIdehyde, 5.31 (52.5 mmoI) of anhydrous triethiamine and 5 g (52.5 mmoIes) of anhydrous MgCl2 in 100 ml of anhydrous THF. After 40 min at 60 ° C, the reaction mixture was cooled to room temperature, diluted with 100 ml of water and acidified to pH 1 with hydrochloric acid. After extraction with ethylacetate and evaporation of the solvent in vacuo, the crude product was purified by flash column chromatography on silica gel (methyl chloride), obtaining 2.0 g (57% yield) of 4-etiIthio-2 -hydroxybenzadehyde as a yellow oil.

1 H-NMR (CDCI3, 8 ppm): 1.40 (t, 3H), 3.05 (q, 2H), 6.58 (s, 1H), 6.59 (d, 1H), 7.40 (d, 1H), 9.80 (s, 1H).

Preparation of 7-etiItio-3-benzoiI coumarin

0.83 g (4.33 mmoI) of benzoi Ethyl acetate and 0.37 g (4.33 mmoI) of piperidine were added at a solution of 0.79 g (4.33 mmoIes) of 4-etiIthio-2-hydroxy -benzaIdehfdo in 10 ml of ethane. The mixture was stirred for two hours at reflux, then cooled. After crystallization at room temperature, the reaction product was collected by 20 filtering, yielding 0.90 g of yellowish crystals (yield 67%).

m.p. 122-124 ° C

1 H-NMR (CDCI3, 8 ppm): 1.45 (t, 3H), 3.08 (q, 2H), 7.18 (d, 2H), 7.42-7.55 (m, 3H), 7.60-7.55 (m, 1H), 7.88 (d, 1H), 8.08 (s, 1H).

Example 7 (comparative)

Preparation of 3-benzoiI-5,7-dimethoxycoumarin

image19

Preparation of 4,6-dimethoxy-2-hydroxy-benzaIdehyde

3 g (19.5 mmoI) of 3,5-dimethoxy-phenoI was added with stirring under nitrogen at a solution of 30 1.76 g (58.2 mmoi) of anhydrous paraformaIdehyde, 5.31 g (52, 5 mmoIes) of anhydrous trietiIamine and 5 g (52.5 mmoIes)

of anhydrous MgCl2 in 100 ml of anhydrous THF. After 40 min at 60 ° C, the reaction mixture was cooled to room temperature, diluted with 100 ml of water and acidified to pH 1 with hydrochloric acid. After extraction with ethyl acetate and evaporation of the solvent in vacuo, the crude product was purified by flash column chromatography on silica gel (methylene chloride), obtaining 0.6 g (yield 17%) of 4,6-dimethoxy -2- 35 hydroxy-benzadehyde as a white solid.

1 H-NMR (CDCI3, 8 ppm): 3.84 (s, 3H), 3.85 (s, 3H), 5.91 (s, 1H), 6.02 (s, 1H), 10.10 ( s, 1H).

Preparation of 3-benzoiI-5,7-dimethoxycoumarin

0.63 g (3.29 mmoI) of benzoi Ethyl acetate and 0.28 g (3.29 mmoI) of piperidine were added at a solution of 40 0.60 g (3.29 mmoI) of 4,6-dimethoxy- 2-hydroxy-benzadehyde in 10 ml of ethane. The mixture was stirred for two

12

5

10

fifteen

twenty

25

hours at reflux, then cooled. After crystallization at room temperature, the reaction product was recovered by filtration, obtaining 0.80 g of white crystals (yield 78%).

m.p. 175-178 ° C

1H-NMR (CDCl3, 8 ppm): 3.92 (s, 6H), 6.30 (s, 1H), 6.47 (s, 1H), 7.45 (t, 2H), 7.87 ( d, 2H), 8.44 (s, 1H).

Example 8 (comparative)

Preparation of 7-methoxy-3- (4-methyl-benzoyl) coumarin

image20

0.4 g (2.60 mmol) of 4-methoxy-2-hydroxybenzaldehyde was added to a solution of 0.5 g (2.60 mmol) of 3-oxo-3-p-tolyl acid methyl ester -propionic (purchased from Aldrich) and 0.22 g (2.60 mmol) of piperidine in 5 ml of ethanol. After 2 hours at reflux, the reaction mixture was cooled. The reaction product, crystallized at room temperature, was recovered by filtration. 0.36 g (50% yield) of product was obtained as a white solid.

1 H-NMR (CDCla, 8 ppm): 2.42 (s, 3H), 3.92 (s, 3H), 6.9 (m, 2H), 7.28 (d, 2H), 7.47 ( d, 1H), 7.78 (d, 2H), 8.05 (s, 1H).

Example 9 (comparative)

Preparation of 3- (4-methylbenzoyl) benzo [f] coumarin

image21

0.4 g (2.60 mmol) of 2-hydroxy-naphthalene 1-carbaldehyde, prepared as documented in Example 5, was added to a solution of 0.5 g (2.60 mmol) of methyl ester of the 3-oxo-3-p-tolyl-propionic acid (purchased from Aldrich) and 0.22 g (2.60 mmol) of piperidine in 5 ml of ethanol. After 2 hours at reflux, the reaction mixture was cooled. The reaction product, crystallized at room temperature, was recovered by filtration. 0.31 g (40% yield) of the product was obtained as a yellow solid.

1H-NMR (CDCla, 8 ppm): 2.44 (s, 3H), 7.30 (d, 2H), 7.52 (d, 1H), 7.60 (t, 1H), 7.71 ( t, 1H), 7.82 (d, 2H), 7.94 (d, 1H), 8.10 (d, 1H), 8.25 (d, 1H), 8.88 (s, 1H).

Example 10

Preparation of 3- (4-tert-butylbenzoyl) -5,7-dimethoxycoumarin

image22

0.6 g (3.21 mmol) of 4,6-dimethoxy-2-hydroxy-benzaldehyde, prepared as documented in Example 7, was added to a solution of 0.81 g (3.21 mmol) of methyl 3- (4-t-butylphenyl) -3-oxo-propanoate, prepared as documented in Example 4, and 0.30 g (3.21 mmol) of piperidine in 5 ml of ethanol. After 2 hours at reflux, the mixture

5

10

fifteen

twenty

25

30

35

40

Reaction was cooled. The reaction product, crystallized at room temperature, was recovered by filtration. 0.55 g (50% yield) of the product was obtained as a white solid.

m.p, 166-168 ° C

1H-NMR (CDCl3, 8 ppm): 1.34 (s, 9H), 3.90 (s, 6H), 6.3 (d, 1H), 6.45 (d, 1H), 7.47 ( d, 2H), 7.80 (d, 2H), 8.40 (s, 1H). Example 11

Preparation of 7- (sec-butylthio) -3-benzoylcoumarin

image23

Preparation of 4- (sec-butylthio) -2-hydroxy-benzaldehyde

7.1 g (39 mmol) of 3- (sec-butylthio) -phenol were added with stirring under nitrogen to a solution of 7.89 g (236 mmol) of anhydrous paraformaldehyde, 14.77 (146 mmol) of anhydrous triethylamine and 5.6 g (58.5 mmol) of anhydrous MgCl2 in 150 ml of anhydrous THF. After 2 hours at 60 ° C, the reaction mixture was cooled to room temperature, diluted with 100 ml of water and acidified to pH 1 with hydrochloric acid.

The product was extracted with ethyl acetate and anhydrated with sodium sulfate.

The solvent was removed by vacuum distillation, obtaining crude 4- (sec-butylthio) -2-hydroxybenzaldehyde as a yellow oil.

1H-NMR (CDCla, 8 ppm): 1.03 (t, 3H), 1.38 (d, 3H), 1.56-1.82 (m, 2H), 3.36 (q, 1H), 6.80-6.90 (m, 2H), 7.47 (d, 1H), 9.75 (s, 1H).

Preparation of 7- (sec-butylthio) -3-benzoyl coumarin

2.74 g (14.2 mmol) of ethyl benzoylacetate and 1.2 g (14.2 mmol) of piperidine were added to a solution of 3 g (14.2 mmol) of 4- (sec-butylthio) -2 -hydroxy-benzaldehyde in 20 ml of ethanol. The mixture was stirred for two hours at reflux, then cooled.

The product was recovered by column chromatography on silica gel (toluene: ethyl acetate 9: 1), obtaining 1.92 g (5.68 mmol, 40% yield) of yellow crystals.

1H-NMR (CDCla, 8 ppm): 1.05 (t, 3H), 1.40 (d, 3H), 1.58-1.84 (m, 2H), 3.40 (q, 1H), 7.15-7.26 (m, 2H), 7.40-7.50 (m, 3H), 7.60 (t, 1H), 7.85 (d, 2H), 8.05 (s, 1 HOUR)

Evaluation of 3-ketocumarin photoinitiators

Transparent formulations

The 3-ketocoumarins of the invention were compared with two prior art 3-ketocoumarins and two photoinitiators commonly used in the art: thioxanthone isopropyl (ITX) and triphenylphosphine oxide (TPO).

The light-curing compositions for the assay were prepared by dissolving the photoinitiators and the co-initiator, Esacure EDB (marketed by Lamberti SpA), at a concentration of 3% by weight each in a mixture 99.5: 0.5 by weight of Ebecryl 605 and Ebecryl 350 (Cytec Industries Inc.),

The light-curing compositions, placed in the sample receptacle of an FT-IR apparatus (FT-IR 430-Jasco), were exposed to an LED source (400 or 385 nm) located at a distance of 65 mm from the sample and with a 30 ° angle. IR spectra were acquired at constant time intervals during photopolymerization and the reduction in time of the area of the peaks in 1408 and 810 cm-1 assigned to the acrylic double bond was determined using the IR logic support.

This allows quantifying the degree of polymerization and, therefore, the efficiency of the photoinitiator.

The results at 385 and 400 nm, expressed as% polymerization with respect to time, are documented in Table 1.

Table 1

 Photoinitiator

 385nm after 1 sec 385nm after 2 sec 400nm after 1 sec 400nm after 2 sec

 ITX *

 76 77 63 67

 TPO *

 63 67 48 66

 Example 1 *

 <5 <5 <5 <5

 Example 2 *

 <5 <5 <5 <5

 Example 3 *

 79 80 64 67

 Example 4

 79 80 63 66

 Example 5

 62 67 48 56

 Example 6

 50 55 46 53

 Example 7 *

 n.d. n.d. 67 69

 * Comparative n.d. = not determined

Turquoise inks

5 The light-curing compositions for the assay were prepared by dissolving the photoinitiators and the Esacure EDB co-initiator at a concentration of 5.0% by weight each in a turquoise ink for inkjet printing.

The light-curing compositions, placed in the sample receptacle of an FT-IR apparatus (FT-IR 430-Jasco), were exposed to an LED source (400 or 385 nm) located at a distance of 65 mm from the sample and 10 with An angle of 30 °. IR spectra were acquired at constant time intervals during photopolymerization and the reduction in time of the area of the peaks in 1408 cm-1 and 810 cm-1 assigned to the acrylic double bond was determined using the IR logic support. This allows quantifying the degree of polymerization and, therefore, the efficiency of the photoinitiator.

The results at 400 and 385 nm, expressed as% polymerization with respect to time, are documented in Table 2.

Table 2

 Photoinitiator

 385nm after 1 sec 385nm after 2 sec 400nm after 1 sec 400nm after 2 sec

 ITX *

 63 80 32 58

 TPO *

 8 13 <5 10

 Example 1*

 <5 <5 <5 <5

 Example 2 *

 <5 <5 <5 <5

 Example 3 *

 21 37 <5 <5

 Example 4

 44 62 <5 <5

 Example 5

 54 80 8 21

 Example 6

 65 83 32 57

 Example 7 *

 24 38 6 12

 Example 8 *

 33 45 0 0

 Example 9 *

 8 16 6 11

 Example 10

 75 83 27 45

 Example 11

 n.d. n.d. 27 55

 * Comparative

The same tests were carried out with the 400 nm LED source using phenylglycine as a co-biaser instead of Esacure EDB at a concentration of 5% by weight.

The results, expressed as% polymerization with respect to time, are documented in Table 3.

20 Table 3

 Photoinitiator

 400nm after 1 sec 400nm after 2 sec

 ITX *

 38 72

 Example 5

 31 55

 Example 6

 41 69

 * Comparative

The results show that the 3-ketocoumarins of the invention have much better yields as photoinitiators with an LED light source, both in transparent and pigmented systems, than the 3- ketocoumarin of the prior art, and have comparable yields with the state photoinitiator. of the technique.

Claims (12)

1. A process for curing light-curing compositions, a process comprising: I) preparing a light-curing composition comprising: a) 50 to 99.9% by weight of at least one ethylenically unsaturated compound; 5 b) 0.1 to 35% by weight of at least one 3-ketocoumarin of formula I: image 1 in which: Ri is a substituted or unsubstituted C2-C12 alkyl group; 10 Cou is a coumarin group of formula: image2 in which: R2, R3, R4 and R5 are, independently of each other, hydrogen; or -S-R7, where R7 is hydrogen, C1-C12 alkyl, C3-C12 alkenyl, substituted or unsubstituted phenyl, aryl or heteroaryl, C5-C6 cycloalkyl, C1-C12 alkyl which is substituted with SH, -N (C1 alkyl -C6) 2, piperidino, morpholino, piperazino, -OH, -O (C1-C12 alkyl), -COOH; or C1-C12 alkoxy; fifteen R6 is hydrogen, a hydroxyl group, an alkyl group having 1 to 4 carbon atoms; or Cou is a substituted or unsubstituted naphtho-coumarin group of formula: image3 image4 image5 with the proviso that at least one of R2, R3, R4 and R5 is different from H and that, when Cou is (a) and at least one of R2, R3, R4 and R5 is C1-C12 alkoxy or when Cou is (b), (c) or (d), R1 is a substituted or unsubstituted C1-C12 alkyl group; 5 10 fifteen twenty 25 30 35 II) photopolymerize the photopolymerizable composition thus obtained with an LED light source that emits at wavelengths between 365 nm and 420 nm. 2. The method of curing light-curing compositions according to Claim 1 wherein the light-curing composition comprises: a) 70 to 98.9% by weight of at least one ethylenically unsaturated compound; b) 0.1 to 20% by weight of at least one 3-ketocoumarin of formula I. 3. The photo curing process of light-curing compositions according to Claim 1 wherein the 3- ketocoumarin of formula I, Cou, is a coumarin group of formula (a) and at least one of R2 R3, R4 and R5 is -S- R7 and R7 is an alkyl group having 1 to 6 carbon atoms. 4. The photo curing process of light-curing compositions according to Claim 1 wherein the 3- ketocoumarin of formula I, Cou, is a coumarin group of formula (a) in which R6 is hydrogen and at least two of R2 R3, R4 and R5 are a C1-C6 alkoxy group. 5. The photo curing process of light-curing compositions according to Claim 1 wherein the 3- ketocoumarin of formula I, Cou, is an unsubstituted naphtho-coumarin group of formula (b), (c) or (d). 6. The photopolymerization process of light-curing compositions according to Claim 1 wherein the light-curing composition further comprises 0.2 to 15% by weight of at least one coinitiator and / or 0.5 to 15% by weight of At least one additional photoinitiator. 7. The photo curing process of light-curing compositions according to Claim 6 wherein the light-curing composition comprises from 70 to 98.9% by weight of at least one light-curing compound, from 0.1 to 10% by weight of at least one - ketocoumarin of formula I, from 1 to 15% by weight of at least one sensitizable photoinitiator and, optionally, from 0.2 to 8% by weight of a coinitiator. 8. The process of curing light-curing compositions according to any one of the preceding claims, wherein the light-curing composition further comprises: c) from 0.01 to 30% by weight of dyes. 9. The process of curing light-curing compositions according to Claim 8 wherein the dyes are dyes for inkjet printing. 10. 3-Ketocoumarins of formula I: image6 in which: R1 is hydrogen or a substituted or unsubstituted C1-C12 alkyl group; Cou is a coumarin group of formula: image7 wherein at least one of R2, R3, R4 and R5 is -S-R7, where R7 is hydrogen, C1-C12 alkyl, C3-C12 alkenyl, phenyl, aryl or substituted or unsubstituted heteroaryl, C5- cycloalkyl C6, C1-C12 alkyl which is substituted with SH, - N (C1-C6 alkyl) 2, piperidino, morpholino, piperazino, -OH, -O (C1-C12 alkyl), -COOH, and R6 is hydrogen, a group hydroxyl or an alkyl group having 1 to 4 carbon atoms. 11.3-Ketocoumarins of formula I according to claim 10 wherein R7 is an alkyl group having 1 to 6 carbon atoms. 12. 3-Ketocoumarins of formula I: image8 in which: R1 is a substituted or unsubstituted C2-C12 alkyl group; Cou is a coumarin group of formula: image9 wherein at least one of R2 R3, R4 and R5 is an alkoxy group having 1 to 6 carbon atoms and R6 is hydrogen, a hydroxyl group or an alkyl group having 1 to 4 carbon atoms; 10 o Cou is a substituted or unsubstituted naphthocoumarin of formula: image10 image11 image12